2013 – present Professor, University of Maryland, Department of Chemistry and Biochemistry, Affiliated at the Department of Chemical and Biomolecular Engineering and the Department of Materials Science and Engineering

2009 – present Invited Professor at the Graduate School of Nanoscience and Technology, KAIST (Korea Advanced Institute of Science and Technology), Korea

Research

Interfaces at Nano/Electrochemistry/Bio

My expertise in nanomaterials synthesis and electrochemistry forms the foundation of my research program. We are in general interested in the meso-architectures with various materials and their unique fundamental properties such as ion/electron transports and chemical/electrochemical behaviors. With the fundamental study, we are also interested in application of these various structures at energy storage, electronic devices, and biomedical fields. Research projects may be categorized into three major areas: (1) synthesis and characterization of heterogeneous meso-architectures with various electronic and/or electrochemical materials and their application to high-power energy storage devices and ultrafast electrochromic display, (2) synthesis and characterization of bio-nanotubes for biomedical applications such as targeted drug delivery and biosensors, and (3) investigation of fundamental physical and chemical properties of well-defined porous nanostructured materials such as diffusions and reactions.

Under the Energy Frontier Research Center (DOE-EFRC) at the University of Maryland since 2009, we study the fundamental scientific issues such as ion/electron transportsion the multifunctional heterogeneous meso-architectures for high-power high-energy storages such as supercapacitors and high-power batteries that will also enable fast charge for high energy electric devices. Substantially improved metrics such as power and energy density per unit volume or weight govern viability and adoption of major solutions, such as the plug-in electric car. Alternative energy sources (solar, wind, etc.) with variable delivery rates underscore an increasingly important need to store the captured energy for power delivery on demand, where temporal profiles of capture and delivery-on-demand are uncorrelated. We are also investigating new electrochemical growth mechanisms of the well-defined heterogeneous thin nanostructures. Thin nanostructure enables us to design extremely fast charge transport devices due to thin nature of wall and well-aligned array structure.

Synthesis and characterization of bio-nanotubes for nanotoxicology and biomedical applications

As an ideal platform for targeted drug delivery, nano-scale drug carrier should have multifunctionality and many other attributes, such as targeting moiety, drug uptake and releasing control, imaging capability, proper small size and size distribution, and non-toxicity. We are opening a new area in the nanomaterial field for the drug delivery through the synthesis of nanotubes by combining the attractive tubular structure with various functionalities such as magnetic, fluorescence, and electrochemical properties. Nanotubes have several advantages as advanced drug carriers. First their inner voids can be used to load large amounts of drug molecules. Their open ends can be used as a gate to control drug release. Secondly differential functionalization can allow selective attachment of moieties to the inside (such as drugs, radionuclides) and outside (targeting moieties). Thirdly they are mechanically robust. Finally, by loading drugs inside the tubes, the outer surface can be kept biocompatible which can prevent aggregation and non-specific adsorption as commonly seen with nanoparticles where hydrophobic drugs are attached to the surface. The drug molecules can also be protected from any unwanted biological reaction such as enzymatic DNA/RNA cleavages. These nanotube can be an ideal candidate for the platform of multifunctional fast and controlled drug delivery through both intravenous and transdermal delivery. However, upon all of these fascinating applications the toxicity study of the nanomaterials is equally important to do in parallel, which we are intensively focusing on. We are synthesizing barcoded silica nanotubes with segments of different diameters that can act as ‘coded labels’ for identifying and tracking biomaterials such as proteins and cells. These shape-coded nanotubes can be used as markers for multiplex biosensing. We are also synthesizing successfully barcoded magnetic nanotubes (BMNTs) for separation and detection of bioanalytes and combining the magnetic barcoded nanotubes with microfluidic channels for the automation of separation and detection.

Diffusion and reaction problems in a confined geometry of silica nanotube

To investigate basic questions surrounding nanofluidics (wetting and dewetting), catalytic reactions and molecular diffusion in a confined nanoscale geometry. We are investigating; (1) Wetting and diffusion problem in a silica nanotube, (2) Catalytic reactions in a catalyst-anchored silica nanotube, (3) Control of atomic layer deposition in nanoscale cylindrical pores.